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Aflatoxin in Corn May Exceed Safe Levels

Livestock Update, October 1998

John B. Hall, Extension Animal Scientist, Beef, Animal and Poultry Sciences, Virginia Tech

As we enter the start of the harvest season, several grain producers and grain elevators are reporting high levels of aflatoxin in corn grown in 1998. The drought conditions in the later half of the summer have created conditions favorable for growth of aflatoxin-producing molds. These high levels of aflatoxin can be both an opportunity and a caution for beef producers.

Chickens, hogs and horses are very sensitive to aflatoxins resulting in extremely poor performance, illness or death. Ruminants can detoxify some aflatoxins. Dairy cattle are not sensitive to most aflatoxins, but aflatoxins are passed into the milk. Milk is closely monitored for aflatoxins and only very small amounts are allowed in milk. Beef cattle can use grains containing aflatoxin with little problem if levels are kept low enough. This means beef producers may be able to buy grains that contain low to moderate levels of aflatoxin at a discount because it can't be used for other classes of livestock.

Aflatoxin levels must be monitored in grain fed to beef cattle. Growing feeder cattle over 400 lb., finishing cattle and open cows fed for slaughter can tolerate levels of 100 ppb in the total diet. Therefore, high aflatoxin grains could be used if diluted with enough "clean" feed. Cattle should not be fed diets containing aflatoxins within 3 weeks of slaughter. Diets fed to all other classes of beef cattle (pregnant cows, lightweight calves lactating cows, etc.) should not exceed 20 ppb of aflatoxin.

Most laboratories that analyze feeds will run aflatoxin tests. These tests generally cost $10 to $20. Grains should be checked for aflatoxin before mixing into the feed to determine the amount of dilution, if any, needed. All diets using aflatoxin-containing grains should also be checked after mixing to ensure safe levels are fed. Used wisely these grains can reduce feed costs for beef producers while reducing losses for grain farmers.

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